Improve dumb tablet detection

Improve dumb tablet detection by checking if BTN_STYLUS or BTN_STYLUS2
(first or second pen barrel button) is present when BTN_TOOL_PEN is not
found.

This enables detection of tablets without explicit tool proximity reporting.
These include at least four UC-Logic tablet models: WP4030U, WP5540U,
WP8060U and PF1209, on which many Genius and Trust models are based.

Signed-off-by: Nikolai Kondrashov <spbnick@gmail.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

src/evdev.c

@@ -1888,7 +1888,9 @@ EvdevProbe(InputInfoPtr pInfo)
         if ((TestBit(ABS_X, pEvdev->abs_bitmask) &&
              TestBit(ABS_Y, pEvdev->abs_bitmask))) {
             xf86Msg(X_PROBED, "%s: Found x and y absolute axes\n", pInfo->name);
-            if (TestBit(BTN_TOOL_PEN, pEvdev->key_bitmask))
+            if (TestBit(BTN_TOOL_PEN, pEvdev->key_bitmask) ||
+                TestBit(BTN_STYLUS, pEvdev->key_bitmask) ||
+                TestBit(BTN_STYLUS2, pEvdev->key_bitmask))
             {
                 xf86Msg(X_PROBED, "%s: Found absolute tablet.\n", pInfo->name);
                 pEvdev->flags |= EVDEV_TABLET;